Skiving of cylindrical gears (also known as “hob peeling”) is a cutting process that has existed for many years, primarily for manufacturing internal ring gears (e.g. see DE 243514). Like honing, skiving uses the relative sliding motion between two “cylindrical gears” whose axes are inclined. A skiving cutter usually looks like a shaping cutter with a helix angle, for example 20°, different than the helix angle of the cylindrical gear to be machined (e.g. US 2011/0268523). Other skiving tools comprise bar- or stick-shaped cutting blades arranged in a cutter head according to a hyperboloid as shown in, for example, US 2012/0282055.
Due to the continuous chip removal in skiving, the process is multiple times faster than shaping and more flexible than broaching, but it presents a challenge to machines and tools. While the roll motion between the cutting edges and the gear tooth slots occurs with the machine spindle RPM, the relative axial cutting motion is generally only about one third of the circumferential speed of the cutter. The cutting components of rolling and cutting which result in a “spiral peeling” are represented by the process designation skiving.
Because of the relatively low dynamic stiffness in the gear trains of mechanical machines as well as the fast wear of uncoated cutters, skiving of cylindrical gears failed to achieve a breakthrough against shaping or hobbing until recently. The latest machine tools with direct drive train and stiff electronic gear boxes present an optimal basis for the skiving process. Complex tool geometry and the latest coating technology have contributed to give the soft skiving of cylindrical gears a recent breakthrough.